The present invention pertains to velocimeters and particularly to laser Doppler velocimeters. More particularly, the invention pertains to semiconductor or solid-state laser Doppler velocimeters.
In the related art, laser Doppler velocimeters have been restricted to the use of visible and near infrared gas lasers because of their coherency and narrow linewidth. Semiconductor or solid-state lasers would be preferred for use in laser Doppler velocimeters because of size and weight considerations. However, the semiconductor or solid state lasers have not been used in Doppler velocimeters because of their relatively large linewidth, i.e., hundreds of megahertz (MHz), which prevents the attainment of a practicable or desired resolution in velocimeters.